msm: ipa: ignore enable_irq_wake return value

Do not fail loading of driver if enable_irq_wake fails. This
will enable driver loading on platforms where PM suspend/resume
support is not ready.

Change-Id: Ic744ca99760251a79eda42ce74a8529ec1f1cd68
Signed-off-by: Ravi Gummadidala <rgummadi@codeaurora.org>